From Halopedia, the Halo Wiki
Cedar (Cedrus) is a genus of coniferous trees in the plant family Pinaceae. They are most closely related to the firs (Abies), sharing a very similar cone structure. They occur at altitudes of 1,500–3200 m on Earth. Some cypress trees are commonly referred to as cedar, and even some small deciduous trees. The terms red cedar and white cedar are often used to reduce confusion, but even those are abused terms that are applied to several related and unrelated species around the world.
Cedar trees were present on the planets Earth, Reach,  Harvest and on Installations 00, 04, and 05.
- ↑ Halo: The Fall of Reach, page 48